Genetic Analysis of Yield and Its Components of B. napus Hybrids Using Resynthesized Rapeseed Lines

Resynthesized rapeseeds obtained by crossing the diploid parents Brassica rapa and Brassica oleracea have significant potential in hybrid breeding because of their higher genetic basis compared with Brassica napus cultivars. In this study, an 8 × 8 complete diallel experiment using four B. napus cultivars (BN) and four resynthesized rapeseed lines (RS) as parents was designed to study heterosis and genetic inheritance for yield components. The results showed that heterosis for yield per plant, the number of pods per plant and number of seeds per pod were high, with means 32.77, 24.49 and 15.71%, respectively. Diallel analysis showed that both additive and dominant effects were significant for yield and yield components. All traits, except for 1 000-seed weight, were significant for b1 mean squares and exhibited directional dominance. Dominant genes had positive effects on yield per plant, pods per plant and 1000-seed weight, and negative effects on seeds per pod (r = −0.86, −0.62, −0.41, and 0.47, respectively). Narrow-sense heritability for yield per plant, pods per plant, and 1 000-seed weight and seeds per pod were 66, 31, 46 and 78% for the four traits, respectively. The F1 hybrids showed considerable yields compared to B. napus cultivars when B. napus cultivars and resynthesized rapeseeds were used as parents (NR hybrids), with many more pods per plant and lower seeds per pod compared with the rapeseed cultivars, indicating that the resynthesized rapeseed may be applicable in current hybrid breeding programs.